Electrical protective device.



B. H. SMITH 61 P. MACGAHAN.

ELECTRICAL PROTECTIVE DEVICE.

APPLICATION FILED NOV. 28, I913- Patented Nov. 14, 1916.

jVorma ZZy Jai'unz fe TN ENTO 5 ATTORNEY WITNESSES:

UNITED sT TEs PATENT OFFICE.

BENJAMIN H. SMITH, or TUBTLEYCREEK, AND PAUL MAQGAHAN, or PITTSBURGH,

PENNSYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC AND MANUFACTURINGCOMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRICAL PROTECTIVE DEVICE.

Specification of Letters Patent.

Patented Nov. 14, 1916.

To all whom it may concern:

Be it known that we, BENJAMIN H. SMITH, a citizen of the United States,and a resident of Turtle Creek, in the county of Allegheny and State ofPenns lvania, and PAUL MAOGAHAN, a citizen 0 the United States, and aresident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in ElectricalProtective Devices, of which the following is a specification.

Our invention relates to electrical protective devices and particularlyto relays.

The object of our invention is to provide a relay device that shall beadapted to trip a circuit interrupter or operate other similar deviceswhen the current that traverses the circuit rises to a predeterminedvalue.

Heretofore, considerable difliculties have been experienced in the useof relays of the series trip type by reason of the fusing of the contactmembers when currents of abnormally large values traverse the same.

To overcome the above mentioned difliculties, we provide, in ourinvention, a device comprising a relay and a transformer having asaturated magnetic circuit for preventing an abnormal rise in the valueof the current that traverses its contact members.

The single figure of the accompanying drawing is a diagrammatic view ofcircuits and devices embodying our invention.

Referring to the drawing, an electrical circuit 1 is interrupted by acircuit interrupter 2 when the current that traverses it exceeds apredetermined value. A series transformer 3 has its primary winding 4connected in series relation to one conductor of the circuit 1 and itssecondary winding 5 connected in circuit with a magnet winding 6 andtheprimary winding 7 of a saturated transformer 8. The secondary winding9 of the transformer 8 is connected in series relation to the windin 10of a tripping electromagnet 11, and it is controlled by contactterminals 12 and a movable bridging member 13 that is attached to themovable core member 14 of an electromagnet 15 upon which the winding 6is disposed.

When a current of an abnormal value traverses the circuit 1, a currentof a corresponding value will traverse the secondary winding 5 of thetransformer 3, and this current will energize the winding 6 of theelectromagnet 15 sufficiently to move the movable core member 1 1 andthe'bridging member 13 upwardly to complete the circuit comprising thesecondary winding 9 of the saturated transformer 8 and the winding 10 ofthe tripping electromagnet 11. Since the primary winding 7 of thetransformer 8 is in circuit with the secondary winding 5 of thetransformer 3, the current traversing the same induces a current of suchvalue in the secondary winding 9 as to cause the tripping electromagnet11 to open the circuit 1 by tripping the circuit interrupter 2.

Since the transformer 8 has a magnetizable core member 16 that becomessaturated when a current of a normal value traverses the circuit 1, acurrent of an excessive value traversing the primary winding 7 will notincrease the value of the current traversing the winding 9 in proportionby reason of the magnetic saturation of the magnetic core member 16, asis familiar to those versed in the art. The current that traverses thesecondary winding 9 increases but the increase is not suflicient to fusethe contact terminals 12 when current of a relatively large valuetraverses the circuit 1. Hence, the difliculties usually experienced inseries trip relays are obviated.

\Vhile we have described a relay for opening a circuit interrupter whichis supplied with energy from a transformer having a saturated magneticcircuit, we desire it to be understood that our invention may be equallyas well applied to the operation of other devices by the employment ofmodifications which do not departfrom the spirit and scope of ourinvention as set forth in the appended claims.

We claim as our invention:

1. An electrical protective device comprising an electromagnet winding,a transformer having a normally saturated core and a primary windingconnected in circuit with said electromagnet winding, a secondarycircuit comprising a secondary winding of the said transformer and anauxiliary actuating device and means actuated by said electromagnetwinding to close said secondary circuit.

2. In a relay, the combination with an electromagnet, of a transformerhaving a .normally saturated core and primary and secondary windings,the said primary winding and the winding of the said electromag netbeing series-connected, and means operated by said electromagnet toclose the circuit of the secondary winding of the said transformer.

3. In an electric circuit, the combination with a circuit interrupter, atripping magnet, and a relay for controlling the circuit of the trippingmagnet, of a magnetically saturated transformer one winding of which isconnected to the circuit through the winding of the relay and the otherwinding of which is connected in circuit with the tripping magnet.

4. In an electrical circuit, the combination with a circuit interrupter,a tripping magnet, and a rela, for controlling the circuit of thetripping magnet, of a normally saturated transformer electricallyconnected to the circuit, the tripping magnet and the winding of therelay for supplying the tripping magnet with a predetermined value ofcurrent irrespective of the current traversing the circuit above apredetermined value.

5. An electrical protective device comprising an electromagnet, atransformer having a normally saturated core, a primary windingconnected to the winding of said electromagnet and a secondary winding,and means operated by the said electromagnet to control the flow ofcurrent through said secondary winding.

6. An electrical protective device comprising an electromagnet, atransformer having primary and secondary windings and a normallysaturated core for preventing the current in the secondary winding fromrising in proportion to the current in the primary winding, said primarywinding being connected in circuit with the electromagnet, and meansoperated by the said electromagnet to control the flow of currentthrough the said secondary winding.

In an electrical protective device, the combination with an electricalcircuit, of a circuit interrupt r having a tripping means comprising anelectromagnet, a relay, a transformer having a normally saturated core,means for supplying the winding of the said relay and the primarywinding of said transformer with current that is proportional to thecurrent traversing the said electrical circuit, means actuated by saidwith a circuit interrupter and a tripping" magnet, of a relay forcontrolling the circuit of the tripping magnet. and inductive meansconnected in circuit with the winding of the relay for controlling thecurrent that traverses the said tripping magnet.

9. In an electric circuit, the combination with an electro-responsivedevice, and means for controlling its circuit in accordance with thecurrent that traverses the circuit, of a normally saturated transformerone winding of which is connected to the circuit through the saidcontrolling means and the other winding of which is connected to theelectro-responsive device for causing it to be supplied with currentdisproportionately to the current that traverses the circuit.

10. In an electrical circuit, the combination with a circuitinterrupter, a tripping magnet, and a relay for controlling the circuitof the tripping magnet, of a normally saturated transformer electricallyconnected to the circuit, the relay and the tripping magnet forsupplying the tripping magnet with a predetermined value of current whenthe current traversing the circuit is above a predetermined value.

11. In an electric circuit, the combination with a circuit interrupter,a tripping magnet, and a relay for controlling the circuit of thetripping magnet, of means 0peratively connected to the circuit forsupplying the tripping magnet with a substantially constant current fromthe circuit, irrespective of the current that traverses the circuit.

12. In an electrical circuit, the combination with an electro-responsivedevice and a relay for controlling the circuit of the electro-responsivedevice, of means operatively connected to the circuit for supplying theelectro-responsive device with a substantially constant predeterminedcurrent from the circuit, irrespective of the current that traverses thecircuit.

13. In an electric circuit, the combination with an electro-responsivedevice and means for closing the circuit of the electroresponsive deviceunder predetermined conditions in the circuit, of means operativelyconnected to the circuit for supplying the electro-responsive devicewith a substantially predetermined constant current from the circuit,irrespective of the current that traverses the circuit above apredetermined value.

14:. In an electric circuit, the combination with an electro-responsivedevice and means for closing the circuit of the electro-responsubscribedour names this 18th day of Nov., sifve device under predeterminfidconditionsi, 1913. 0 means connected between t e circuit an T w theelectro-responsive device for causing it 35 to be supplied with currentfrom the cira cuit disproportionately to the current that \Vitnesses:traverses the circuit. B. B. HINES,

In testimony whereof, we have hereunto M. C. MERZ.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

